MgSO4 is chosen as an additive to address the capacity fading issue in the rechargeable zinc-ion battery system of -MgxV2O5·nH2O//ZnSO4//zinc. Elec-trolytes with different concentration ratios of -ZnSO4 and -MgSO4 are investigated. The batteries measured in the 1 M -ZnSO4?1 M -MgSO4 electrolyte outplay other competitors, which deliver a high specific capacity of 374 mAh -g?1 at a current density of 100 mA -g?1 and exhibit a competitive rate performance with the revers-ible capacity of 175 mAh -g?1 at 5 A -g?1. This study provides a promising route to improve the performance of vanadium-based cathodes for aqueous zinc-ion batteries with electrolyte optimization in cost-effective electrolytes.